U.S. patent application number 13/845141 was filed with the patent office on 2014-06-12 for busbar that can be integrated into an electric motor.
This patent application is currently assigned to MERSEN FRANCE SB SAS. The applicant listed for this patent is MERSEN FRANCE SB SAS. Invention is credited to Francois ANNE, Herve FORVEILLE.
Application Number | 20140159519 13/845141 |
Document ID | / |
Family ID | 47741127 |
Filed Date | 2014-06-12 |
United States Patent
Application |
20140159519 |
Kind Code |
A1 |
FORVEILLE; Herve ; et
al. |
June 12, 2014 |
BUSBAR THAT CAN BE INTEGRATED INTO AN ELECTRIC MOTOR
Abstract
This busbar (1) includes at least two conductive elements (10,
16, 20, 26, 30, 36, 40) which include electrical connection
elements (14, 24, 34, 18, 28, 38, 44) of windings belonging to the
stator of an electric machine. All of the conductive elements (10,
16, 20, 26, 30, 36, 40) are each cut out from a plate of
electrically conduction material, bent according to a direction
perpendicular to the thickness of the plate and radially
superimposed in relation to a central axis (Y-Y) that is common to
the conductive elements (10, 16, 20, 26, 30, 36, 40).
Inventors: |
FORVEILLE; Herve; (Gene,
FR) ; ANNE; Francois; (Angers, FR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MERSEN FRANCE SB SAS |
Saint-Bonnet-de-Mure |
|
FR |
|
|
Assignee: |
MERSEN FRANCE SB SAS
Saint-Bonnet-de-Mure
FR
|
Family ID: |
47741127 |
Appl. No.: |
13/845141 |
Filed: |
March 18, 2013 |
Current U.S.
Class: |
310/71 ;
29/874 |
Current CPC
Class: |
H02K 3/28 20130101; H02K
2203/09 20130101; Y10T 29/49204 20150115; H02K 3/522 20130101 |
Class at
Publication: |
310/71 ;
29/874 |
International
Class: |
H02K 3/28 20060101
H02K003/28; H02K 15/00 20060101 H02K015/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 11, 2012 |
FR |
12 61893 |
Claims
1. Busbar comprising at least two conductive elements which
comprise electrical connection means of windings belonging to the
stator of an electric machine, wherein all of the conductive are
each cut out of a plate of electrically conductive material, bent
according to a direction perpendicular to the thickness of the
plate and radially superimposed in relation to a central axis
common to the conductive elements.
2. Busbar according to claim 1, wherein all of the conductive
elements of the busbar have a circular profile.
3. Busbar according to claim 1, wherein all of the conductive
elements of the busbar have a polygonal profile.
4. Busbar as claimed in claim 1, wherein at least one of the
conductive elements of the busbar extends on an angle strictly less
than 360.degree. around the common central axis.
5. Busbar as claimed in claim 1, wherein the electrical connection
means are output lugs all oriented in the same direction, along the
common axis and in relation to the conductive elements.
6. Busbar as claimed in claim 1, wherein the busbar comprises at
least one layer of electrical insulation which is radially arranged
between the two conductive elements of each pair of conductive
elements radially superimposed in relation to the central axis or
inside the conductive element the most internal to the busbar or
around the conductive element the most external to the busbar.
7. Electric machine comprising: a stator which comprises a
cylindrical and hollow core and at least two groups of at least one
winding, respectively associated with a phase of the electric
machine, a rotor which rotates coaxially inside the stator, wherein
the electric machine further comprises a busbar in accordance with
claim 1, and of which the common central axis is confounded with
the axis of the stator.
8. Electric machine according to claim 7 wherein each group of
windings comprises several windings and in that several conductive
elements of the busbar are connected to the windings of the same
group.
9. Electric machine according to claim 7, wherein all of the groups
of windings of the stator are connected to a neutral conductor of
the busbar.
10. Electric machine according to claim 7, wherein the output lugs
of the conductive elements are angularly arranged around the axis
of the stator in such a way that, in the assembled configuration of
the busbar on the stator, each output lug is located axially at the
opposite of at least one output of a winding.
11. Method for manufacturing a busbar in accordance with claim 1,
wherein it comprises steps consisting in: a) cutting out from an
electrically conductive plate a strip of material for each
conductive element. b) affixing a layer of electrical insulation on
each strip c) bending each strip according to a direction
perpendicular to its thickness in such a way as to centre the strip
on an axis.
12. Method according to claim 11, wherein the latter further
comprises a step d) posterior to the step c), consisting in
aligning all of the axes whereon the strips are centred in order to
form a common central axis, then in nesting the conductive elements
by radial superposition of the conductive elements around the
common axis.
13. Method according to claim 11, wherein it further comprises a
step e), posterior to the step b) and prior to the step c),
consisting in stacking the conductive elements on one another,
according to a direction perpendicular to their thickness.
Description
[0001] The invention relates to a busbar intended to be integrated
into an electric machine. Electric machine means a motor or a
generator, and even a motor-generator that can function both as a
motor and generator.
[0002] A busbar is a set of conductive elements provided with
electrical connection means. In the field of power electronics, a
busbar is often used for high current values where traditional
electrical connection means, such as cables or printed circuits,
are no longer suited. This because the conductive elements of a
busbar most often have a particular geometry such as a tube or a
bar and are not very thick in order to accentuate the skin effect
and as such dissipate the least amount of energy possible. The
invention is interesting in the event it is desired to connect
together the windings of the stator of an electric machine. For the
purposes of simplification, the case wherein the electric machine
is a motor shall be covered here, although the invention also
applies to generators or to motor-generators.
[0003] It is known that the stator of an electric machine can
receive several groups of windings or coils according to the number
of phases of the motor. In an electric motor, the connection of the
windings to the electricity network is carried out by means of a
terminal block, which is a device that makes it possible to provide
for the electrical continuity of the output cables of the windings
to the mains. This terminal block is included in the motor and
protected by a casing fixed on the motor. Each winding comprises
one or several flat or winding wires, more preferably made of
copper and all of the wires are wound in the same way, with each
wire having two ends, with all the ends on either side of the wires
constituting the two outputs of a winding. To do this, according to
a known technique, the windings of a group of windings are
connected together by the intermediary of cables, with each of them
having a section determined according to the power of the motor.
According to the type of terminal block, the outputs of the
windings are then doubled or even tripled. This creates a problem
of space, assembly time and cost of raw materials, as well as
reliability since the risk of a cabling error is high.
[0004] A motor using cables is moreover relatively heavy, of great
size and has a high inductance. Indeed, using cables imposes that
the manufacturer should solder the end of the cables to the
terminal block. As solder constituting resistances oppose the
electric current, it is then suitable to use windings that have a
higher inductance, in order to take into account the losses in
electrical energy linked to the solder. However, using a high
inductance implies that at high frequencies, the windings oppose a
strong resistance to the passage of the current. The electric
current passing through the windings is therefore low, in the same
way as the motor torque which is directly proportional to it.
[0005] It is these disadvantages that the invention intends more
particularly to overcome by proposing a busbar that is easily
integrated into an electric machine in order to connected together
the windings of the stator of this machine.
[0006] To this effect the invention relates to a busbar comprising
at least two conductive elements which comprise electrical
connection means of windings belonging to the stator of an electric
machine, characterised in that all of the conductive elements are
each cut out from a plate of electrically conductive material, bent
according to a direction perpendicular to the thickness of the
plate and radially superimposed in relation to a central axis that
is common to the conductive elements.
[0007] Thanks to the invention, it is possible to connect the
windings of the same group of windings together in a manner that
takes up less space, that is more economical, simpler to assemble
and more reliable. The invention also makes it possible to simplify
the connection of a group of windings to the terminal block of an
electric machine.
[0008] According to advantageous but not mandatory aspects of the
invention, a busbar can incorporate one or several of the following
characteristics, taken in any technically permissible combination:
[0009] All of the conductive elements of the busbar have a circular
profile. [0010] All of the conductive elements of the busbar have a
polygonal profile. [0011] At least one of the conductive elements
of the busbar extends over an angle strictly less than 360.degree.
around the common central axis. [0012] The electrical connection
means are output lugs all directed in the same direction, along the
common axis and in relation to the conductive elements. [0013] The
busbar comprises at least one layer of electrical insulation which
is radially arranged between two conductive elements of each pair
of conductive elements radially superimposed in relation to the
central axis or inside the conductive element the most internal to
the busbar or around the conductive element the most external to
the busbar.
[0014] The invention further relates to an electric machine
comprising a stator which comprises a cylindrical and hollow core,
and at least two groups of at least one winding, respectively
associated to a phase of the electric machine and a rotor which
rotates coaxially inside the stator. This machine is characterised
in that it further comprises a busbar such as mentioned hereinabove
and of which the common central axis is confounded with the axis of
the stator.
[0015] As such, it is possible to easily integrate the busbar into
the electric machine, without however substantially making it
heavy, or even increasing the dimensions of the machine.
[0016] According to advantageous but not mandatory aspects of the
invention, such an electric machine can incorporate one or several
of the following characteristics, taken in any technically
permissible combination: [0017] Each group of windings comprises
several windings and several conductive elements of the busbar are
connected to the windings of the same group. [0018] All of the
groups of windings of the stator are connected to a neutral
conductor of the busbar. [0019] The output lugs of the conductive
elements are angularly arranged around the axis of the stator in
such a way that, in an assembled configuration of the busbar on the
stator, each output lug is located axially opposite at least one
output of a winding.
[0020] The invention finally relates to a method of manufacturing a
busbar such as described hereinabove, characterised in that it
comprises steps consisting in: [0021] a) cutting out of from an
electrically conductive plate a strip of material for each
conductive element [0022] b) affixing a layer of electrical
insulation on each strip [0023] c) winding each strip according to
a direction perpendicular to its thickness in such a way as to
centre the strip on an axis.
[0024] According to advantageous but not mandatory aspects of the
invention, such a method can incorporate one or several of the
following characteristics, taken in any technically permissible
combination: [0025] This method further comprises a step d)
posterior to the step c), consisting in aligning all of the axes
whereon the strips are centred in order to form a common central
axis, then in nesting the conductive elements via radial
superposition of the conductive elements around the common axis.
[0026] This method further comprises a step e), posterior to the
step b) and prior to the step c), consisting in stacking the
conductive elements on top of each other, according to a direction
perpendicular to their thickness.
[0027] The invention shall be better understood and other
advantages of the latter shall appear more clearly when reading the
following description of two embodiments of a busbar and of an
electric motor in accordance with its principle, provided by way of
example and made in reference to the annexed drawings wherein:
[0028] FIG. 1 is an exploded perspective block diagram of an
electric motor in accordance with the invention incorporating a
busbar in accordance with the invention,
[0029] FIG. 2 is a perspective view on a larger scale of the busbar
of the motor of FIG. 1, under a viewing angle different from that
of FIG. 1,
[0030] FIG. 3 is an exploded perspective view of the busbar of FIG.
1,
[0031] FIG. 4 is an overhead view according to the arrow IV of FIG.
2,
[0032] FIG. 5 is a view on a larger scale of the encircled zone V
in FIG. 4 and,
[0033] FIG. 6 is a view similar to FIG. 3, for a busbar in
accordance with a second embodiment of the invention.
[0034] FIG. 1 shows a motor M comprising on the one hand, a stator
S which includes, on the one hand, a cylindrical and hollow core 3,
centred on a geometrical axis X-X, and, on the other hand, a rotor
R, which is mounted inside the stator S rotating about itself
around the axis X-X.
[0035] The stator S is provided with windings. More precisely, the
aforementioned cylindrical and hollow core 3 comprises twenty-four
notches receiving twelve windings or coils which are distributed
around the axis X-X of the core 3, i.e. extending over a portion of
the core 3. Generally, the number of windings as well as the number
of notches used depends on the power of the motor. Recall that a
winding is a rolling of one or several winding wires, often made of
copper, around a geometry defined by the two aforementioned
notches. In the example, a group of windings comprises four
windings B.sub.1, B.sub.2, B.sub.3 and B.sub.4. However, the number
of windings used in a group of windings also depends on the power
of the motor.
[0036] In FIG. 1, only one group of windings is shown, for reasons
of clarity of the drawing, and the windings B.sub.1 to B.sub.4 are
figured by a few windings, although in reality they comprise many
windings.
[0037] The windings B.sub.1, B.sub.2, B.sub.3 and B.sub.4 each
include two outputs, defined by the two ends of the winding wire or
wires that they are comprised of and respectively denoted as
E.sub.11 and E.sub.12, E.sub.21 and E.sub.22, E.sub.31 and E.sub.32
and E.sub.41 and E.sub.42. Moreover, the motor M which is
triple-phased, is provided with three groups of windings each
corresponding to a phase of the motor. The windings of a group of
windings are connected together, in series or in parallel according
to the electrical diagram selected, and an alternating current
flows through them. As mentioned previously, the connection of the
windings B.sub.1 to B.sub.4 and equivalents of the stator S to the
mains is carried out by means of a terminal block not shown and
belonging to the motor M.
[0038] For the three-phased motor M, the terminal block comprises
three phase terminals, each corresponding to a phase of the mains
and a neutral terminal, normally connected to the ground. As such,
the stator S carries two groups of windings, similar to that formed
by the windings B.sub.1 to B.sub.4, with these two groups of
windings not being shown.
[0039] Each group of windings has an output intended to be
connected to the corresponding electrical phase as well as to at
least one output intended to be connected to the neutral of the
terminal block.
[0040] In addition, as shown in FIG. 1, the motor M comprises a
busbar 1 which electrically connects the windings of the stator S
together and to the terminal block. This busbar 1 is shown alone in
the FIGS. 2 to 5 and details shall be provided hereinafter. In the
motor M in the assembled state, the busbar 1 is inserted inside an
axial end of the core 3, i.e. that visible in FIG. 1.
[0041] The busbar 1 comprises several conductive elements assembled
geometrically and/or electrically with one another. In the present
case, the conductive elements are portions of rings all with
different diameters, which are centred around a common central axis
Y-Y, which, in assembled configuration of the busbar 1 on the
stator 3, is confounded with the longitudinal axis X-X of the
stator S. The rings of the busbar 1 are of a number of seven and
each have a circular profile, extending over an angle less than
360.degree. around the common axis Y-Y. Using rings with a circular
section astutely makes it possible to reduce the material cost.
[0042] Moreover, a layer of electrical insulation, 101 shown solely
in FIG. 5, is arranged between each pair of two adjacent rings
and/or on the inner surface and/or on the outer surface of the
busbar 1 in order to prevent any short-circuit or poor circulation
of the current.
[0043] The rings 10, 20, and 30 which are on the left portion of
FIG. 3, are rings intended to be connected to the terminal block of
the motor M, not shown in the figures. As such, each of these rings
10, 20 and 30 comprises an input terminal, respectively denoted 12,
22 and 32 corresponding to a phase of the motor. It is therefore
understood that using such a busbar 1 has for advantage to suppress
the cables used in double or in triplicate, which beforehand made
it possible to provide for the connection to the terminal
block.
[0044] These rings 10, 20 and 30 each further include one or
several output lugs, respectively denoted 14, 24 and 34 intended to
be connected to the windings of the stator.
[0045] In the present case, it is therefore understood that having
two output lugs on the rings 10, 20 and 30 corresponds to a
parallel connection, inversely, the presence of a single output lug
would imply a connection in series.
[0046] The three following rings in order starting from the left,
16, 26 and 36 are rings for putting in series or for putting in
parallel, according to the electrical diagram of the motor M. These
rings specific to the type of electrical diagram are called
interconnection rings. Each of these interconnection rings 16, 26
and 36 further include input/output lugs, respectively denoted 18,
28 and 38 which are used as a point of electrical connection of the
ends of the windings of the stator 3. In this example, they are of
a number of four on each interconnection ring 16, 26 and 36, but
this depends on the number of windings in a group of windings and
therefore on the power of the motor. The interconnection rings 16,
26 and 36 therefore do not comprise an input terminal that can be
connected to the terminal block and are designed in such a way
that, in the assembled configuration of the busbar 1 on the stator
3, they are respectively connected electrically to the rings 10, 20
and 30 through a winding. Indeed, the two output lugs 14, 24 and 34
are each connected, independently and respectively through a
winding, to an output lug 18, 28 and 38 belonging to the
corresponding interconnection ring 16, 26 and 36.
[0047] The first ring starting from the right in FIG. 3 is a ring
40 intended to be connected to the neutral of the terminal block.
Indeed, it is necessary in order to close the electrical circuit of
each phase that each group of windings, is connected to the neutral
of the terminal block. That is why the busbar 1 comprises, in the
case of a three-phase motor, the ring 40, providing the connection
of each group of windings to the neutral of the terminal block. For
this, the ring 40 comprises an input terminal 42, making it
possible to connect the ring 40 to the neutral of the terminal
block.
[0048] For a parallel connection, two windings are required to
connect each branch in parallel to the neutral terminal For three
phases, six windings are then connected to the neutral terminal.
That is why the ring 40 connected to the neutral terminal of the
power supply comprises six output lugs, denoted 44.
[0049] The output lugs 14, 24, 34, 44, 18, 28 and 38 are crimped
around winding wires of the windings of the stator S by means of a
clamp which also makes it possible to melt the varnish in order to
provide the electrical contact. As an alternative, it is also
possible, in order to provide the electrical contact, to solder the
end of the winding wires onto the output lugs 14, 24, 34, 18, 28,
38 and 44 or to immobilise the winding wires in ring terminals
which are then screwed onto the output lugs 14, 24, 34, 18, 28, 38
and 44 each one provided with a suitable tapping.
[0050] The rings 10, 20, 30, 16, 26, 36 and 40 are all obtained
using plates of a conductive material. With a concern for clarity,
only the method of manufacturing the ring 10 is described
hereinbelow, this method is applied by transposition to the other
rings 20, 30, 40, 16, 26 and 36. In a first step, a plate of
conductive material, for example a plate of sheet metal, is cut out
in the shape of a strip, by preserving the input terminal 12 and
the output lugs 14. Then, a layer of electrical insulation 101 is
affixed on this strip. The fixing of the layer of electrical
insulation 101 on the strip can take place via any suitable
technique, in particular via rolling. So, a rolled strip is a strip
on which a layer of electrical insulation is affixed.
[0051] Finally, this strip provided with a layer of insulation is
bent according to a direction F2, perpendicular to the thickness of
the plate, and around a central axis Y10 which, in configuration of
the busbar 1, is confounded with the central axis Y-Y of the
busbar.
[0052] The same type of operations are repeated for cutting,
providing with a layer of insulation and bending or "rolling" the
strips 20, 30, 16, 26, 36 and 40.
[0053] In order to provide more precise details on the connection
of the windings of the stator S, we shall focus, for the purposes
of simplification, on the electrical connection of the group of
windings B.sub.1, B.sub.2, B.sub.3 and B.sub.4, and we shall
consider that the rings 10 and 16 are associated with this group.
In addition, note for the clarity of the description, 14a and 14b
the two output lugs 14 of the ring 10 and 18a, 18b, 18c and 18d the
four output lugs 18 of the ring 16. Note also 44a and 44b two
output lugs among the output lugs 44.
[0054] As such, it is understood that the end E.sub.11 of the
winding B.sub.1 is crimped in the output lug 14a of the ring 10 and
the end E.sub.12 is crimped in the output lug 18a. In parallel, the
end E.sub.21 of the winding B.sub.2 is crimped in the output lug
14b of the ring 10 and the end E.sub.22 is crimped in the output
lug 18b. In order to complete the circuit, the two remaining
windings B.sub.3 and B.sub.4 have their ends E.sub.31 and E.sub.32
and E.sub.41 and E.sub.42 respectively crimped in the output lugs
18c and 44a and 18d and 44b. Moreover, the connection of this group
of windings is not limited to the example mentioned hereinabove as
all of the combinations are possible.
[0055] As such, the output lug 14a or 14b can very well be
connected to one of the output lugs 18a, 18b or 18d and, similarly,
two of the output lugs 18a, 18b, 18c and 18d can be connected to
two of the output lugs 44a and 44b indifferently.
[0056] On the other hand, there is still a preferred combination
which is to connect the end of the windings directly with the
output lug axially opposite. This makes it possible to limit the
space used by the connection between the windings and the output
lugs. To this effect, the busbar 1 is designed in such a way that,
in the assembled configuration of the busbar 1, as shown in FIG. 2,
each output lug 14, 24, 34, 18, 28, 38 and 44 respectively rings
10, 20, 30, 16, 26, 36 and 40, is angularly arranged around the
axis X-X, so that it is located axially at the opposite of an end
of a winding.
[0057] The alignment of the rings 10, 20, 30, 16, 26, 36 and 40 in
relation to one another brings the busbar into the configuration of
FIG. 3. In this configuration, the axes Y10, Y20, Y30, Y16, Y26,
Y36 and Y40 whereon the rings 10, 20, 30, 16, 26, 36 and 40 have
been respectively centred are all confounded with the axis Y-Y. It
is then suitable to elastically deform the rings so as to be able
to radially superimpose them and bring the busbar into the
configuration of FIG. 2. This elastic deformation is favoured by
the fact that the rings 10, 20, 30, 16, 26, 36 and 40 extend over
less than 360.degree., respectively around the axes Y10, Y20, Y30,
Y16, Y26, Y36 and Y40. More precisely, a ring 10 extends on an
angle of about 180.degree. respectively around the axis Y10, while
the rings 20, 30, 16, 26 and 36 extend over an angle of about
270.degree. respectively around the axes Y20, Y30, Y16, Y26 and
Y36, and the ring 40 extends over an angle of about 350.degree.
around the axis Y40. However, in terms of an alternative not shown,
it is possible that one or several rings of the busbar 1 are closed
and extend therefore over 360.degree.. Here, it can be considered
that the ring 40 is closed instead of extending over about
350.degree.. In addition, deforming the rings 10, 20, 30, 16, 26,
36 and 40 elastically implies that the elastic return, exerting
according to a radial direction around the central axis Y-Y, of
this deformation tends to improve the mechanical strength of the
busbar 1 in its assembled configuration as the latter is under
stress.
[0058] In opposition with a complete assembly of the individual
rings 10, 20, 30, 16, 26, 36, 40, it is also possible to assemble
the busbar 1 using several rolled multi-conductor rings each
comprising several conductive layers, forming conductors, and
several layers of insulation. These multi-conductor rings are bent.
More precisely, it can be imagined to roll, that is affixing a
layer of electrical insulation, then bend a few single-conductor
rings together, such as for example the rings 10, 20 and 30, as
such forming a multi-conductor ring, carrying out the same
operation for the rings 16, 26, 36 and 40 then to assemble the two
multi-conductor rings formed as such. Naturally, this method of
assembly is not limited to the assembly of two multi-conductor
rings, the number of multi-conductor rings to be assembled being
determined in order to simplify the method of manufacture.
[0059] A third possibility is to roll all of the strips using
layers of insulation, then to superimpose the strips and finally to
bend all of the strips and layers together, in order to give the
busbar 1 a shape centred on the common central axis Y-Y.
[0060] In addition, in terms of an alternative not shown, it is
possible to add a layer of electrical insulation on the inner
surface of the ring 20 the most internal to the busbar 1 and a
layer of electrical insulation on the external surface of the ring
30 the most external to the busbar 1.
[0061] Moreover, it is necessary, during the assembly to position
all of the output lugs 14, 24, 34, 18, 28, 38 and 44 in the same
direction F1, which is a longitudinal direction oriented from the
left to the right along the axis Y-Y in FIG. 3, and this in order
to prevent an assembly error.
[0062] In addition, it is suitable to arrange each output 12, 22,
32 and 42 intended to be connected to the terminal block side by
side. The connection of the busbar 1 to the terminal block will as
such be facilitated.
[0063] Note that the order of radial superposition of the rings 10,
20, 30, 16, 26, 36 and 40 of the busbar 1, better shown in FIG. 5,
is important, since each ring 10, 20, 30, 16, 26, 36, 40 has a
different diameter, and that this constitutes a mechanical
fool-proof device making it possible to comply with the stacking
order of the rings 10, 20, 30, 40, 16, 26 and 36. In addition, each
ring is arranged, angularly in a precise manner, so that each
output lug 14, 18, 24, 28, 34, 38, 44 of the rings 10, 20, 30, 16,
26, 36 and 40 is axially opposite the output of the corresponding
winding. It is therefore understood that there is only one way to
assemble the busbar 1.
[0064] Other embodiments can be considered concerning this
invention. By way of example, it is possible to use solely one ring
10, 20, 30 per phase, without using interconnection rings 16, 26,
36.
[0065] Another embodiment resides in the use of a busbar 1', of a
shape that is not circular, but polygonal, shown as an exploded
view in FIG. 6, wherein each ring of the busbar 1' is folded in the
shape of a polygon which may be uninterrupted. Indeed, if one takes
the example of the conductive element 10, the latter is cut out of
a plate of conductive material by taking care to preserve the
electrical connection means, then is rolled with a layer of
electrical insulation and finally wound around a central axis, by
means of several folding operations.
[0066] It is therefore understood that the bending of a conductive
element 10 or equivalent can be interpreted, either as a
deformation aiming to give the conductive element 10 a circular or
rounded shape, or as several folding operations aiming to give the
conductive element 10 a polygonal shape.
[0067] In the case of FIG. 6, four folding operations are carried
out, perpendicularly to the thickness of the conductive element 10
and according to four different directions F.sub.3, F.sub.4,
F.sub.5 and F.sub.6. The invention can be carried out regardless of
the number of foldings, as long as the number and the folding zones
are the same for all of the conductive elements 10, 20, 30, 16, 26,
36 and 40.
[0068] When all of the conductive elements are each respectively
wound or bent, around their central axis, it is suitable to align
them around a common central axis Y-Y then to reassemble them via
radial superposition in relation to this common central axis Y-Y,
as in the first embodiment.
[0069] Moreover, in this embodiment, the connection of the output
lugs 14, 24, 34, 18, 28, 38 and 44 is carried out by means of nuts
and bolts as shown by the threaded holes 5, shown by way of example
solely on the ring 30 of FIG. 6 but which are arranged on each of
the rings 10, 20, 30, 40, 16, 26 and 36. These threaded holes 5
pass through the output lugs 14, 24, 34, 18, 28, 38 and 44 and are
intended to receive the tightening screws.
[0070] In the preceding description, the electric motor M is
three-phased as this embodiment lends itself well to the use of the
busbar 1. However, this does not means that the invention is
limited to this embodiment: the invention also has application in
motors of the single-phase type, and even comprising a number of
phases strictly greater than three.
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